The mast lights isolation transformer provides an air gap between the primary and secondary. The primary of the transformer is at ground potential, the secondary is at RF potential.
Absolutely use for isolation these are required in at least some radio broadcasting installations where are tower lights not sure if this is 100% always but but I'm aware of how the system works and as to how some radio transmission antennas do you need to be isolated from ground AKA insulated from ground. For example some radio towers themselves are also an antenna in some setups. All kinds of weird stuff can happen with RF and broadcasting and more. For example years and years ago at one of the churches I attended for folks and my father worked there. Every time an emergency vehicle would pass you actually hear the emergency radio on the PA system apparently it had something to do with certain parts not being shielded properly or not properly connected regarding shielding. It was said several times that it may have had something to do with actually eat the output wiring not the input which I kind of doubt it's dubious that had to do with the speaker end of things with the wiring since that almost makes no sense but I suppose that if something was not quite right or otherwise something weird going on could be a factor. The weird thing is that was the only thing that would come through on the system no other type of Mobile Radio interference almost like that someone was just the right length or something was acting as an incidental tuner and happen to be Quorum Court accidentally receiving this frequency. It was only one of the emergency services in the area no other types of radio or anything just confirming this. There was one of the other things of interest I remember years ago living in a townhouse in Wisconsin for a while. There was a pretty high power radio station just literally probably capital city blocks don't know how far it actually was it was hard to tell from looking out a window you know. But I can tell you you would actually hear that radio station on all kinds of stuff that was not intended to even receive radio. Even occasionally when you pick up the way my phone and it's quiet you would even hear the station playing in the background! It wasn't always just equipment that was just cheaply made or older you would even get some stuff on unintended things even if a bit better built. It's not what was being transmitted that was a problem it was what was receiving it accidentally what's the actual issue. Not the first time I've seen something like this and heard about it either on a personal basis that was. Also that Rusty bolt affect with interference is really something else give me a real head scratcher for someone as well I knew someone that had this problem and that was damaged radio operator literally just a bad bones of connection on the tower that was causing interference that one for sure if you don't know what you're looking for could really rack your brain
In the 70s and 80s in a city in South Florida, two of the telephone switching Central Offices, had massive amounts of AM RF from an AM radio station @ 50,000 watts day pattern 8 miles away. We were a user of dedicated Radio Pairs from our Public Safety Radio Network in the CO. We had to use grounding, Chokes, ferrite beads, the works to suppress it.. Good times @@aaronbrandenburg2441
Directional AM arrays are very common in North America. They have been used since the 1930s to both increase the signal strength in the direction of desired coverage areas and to reduce it in the direction of other stations on the same frequency. And nearby power lines and cell phone towers do often cause problems with the directional pattern and require detuning. One AM station here in NJ recently gave up using their directional nighttime signal and reverted to a less powerful non-directional signal due to constant problems with this, and because most of their listeners are now tuning in their FM translators instead of the AM signal.
Saffron Green is still being used for LBC. When you drive past it on The A1, which is north and west of the site, the signal drops significantly as you pass the array.
I'm less than two miles from that site and I've been an SDR hobbyist for about 8 years now. I went though a phase of chasing NDB signals and I presume it was those transmitters that would sometimes bleed over into the 350-550 kHz part of the spectrum. I concluded that they must turn the signal strength up and down according to the time of day and the atmospheric conditions. As an aside, I can still pick up a raspy signal from those powerlines, in the LF and VLF bands. They run less than mile from my house. Rain seems to play a part in that, possibly just in the fact that I have a better earth when the soil is wet. I've walked around that area several times. There does not seem to be an actual place called Saffron Green, nor is there a clear history about a place with that name. There are one or two scattered houses and caravans there and there is a primary school with that name, nearby in Borehamwood. It's an odd name when you think about it - yellow green! Just like the grass around the towers. Those warning lights are important, the masts are near the approach for Elstree Aerodrome.
I have an AM transmitter less than a mile away, and have observed something similar to what you have. I think I’ll start logging my findings from day to day
@@ShawnWrona I'm guessing it's also a result of the front end of the receiver. Like everything else, the more you pay the better it is! I'm using an Airspy Discovery, which really is very good for the price, but I think there are other higher priced receivers that would not get so easily overwhelmed. I think when you are close to a large transmitter, especially with a long-wire antenna, the ground wave can be very strong. In terms of the transmitter control, I imagine they have some kind of measurement around the periphery of the area they intend, or indeed are contracted, to cover. The site here looks overgrown and dilapidated, but I would think there is some kind of remote monitoring and control. Propagation conditions must vary and it seems logical they would adjust the signal strength accordingly.
virticle structures can be detuned. They get a skirt attached to the structute. The reactance is measured and an appropriate amount of inductance or capacitance is added to cancel th X on the structure. fine tuning can be acomplished with a field intensity meter.
The Toroid coils are known as austin ring transformers, as you mentioned they decouple the AC service from being directly connected to the tower, in order to feed the tower lighting. Also notice the 2 ball looking devices next to the transformer. Those are adjusted to create a spark gap that will dissipate lighting strikes to ground. The detuning process is typically running wires from top to bottom with a tuning unit somewhere (usually at the base), without a lot of techno babble, it's tuned to make the tower essentially invisible at the operating frequency (s) of the nearby transmitter. The goal is to reduce or eliminate reradiation that would effect the pattern of the directional array.
No no, this is absolutely the audience that likes techno babble. Hit me with it, man..... I kind of get what they're doing, my question is how do the tuning boxes achieve making the tower effectively non-reactive to the signal....or, I suppose transparent (which sounds like they let the tower resonate, but only slightly so that to the RF wave there is effectively no change in 'refractive index' (IDK if thats right for RF, but ya know....the thing photons do, but RF) across the towers location)? Full disclosure, I know the secret of all RF technicians.....In order to get your final certification level you have to sacrifice a chicken over your tool bags. Only then can you begin practicing the deep dark RF voodoo.....
@@TankR It's mostly black magic but the end game is to make the subject tower non-resonant at some frequency, typically where there is a standard broadcast transmitter nearby. The AM transmitter can radiate a significant amount of power (depending on licensed power, antenna configuration, etc.) up to a couple of miles from the transmitter site. If there is another tower nearby, some of that power can be re-radiated, thus skewing or distorting the original AM signal. There's a decent amount of information out there, google "detuning skirts" you'll find all kinds of info about the theory and implementation behind them. Interestingly the theory behind detuning stray towers is also utilized with certain AM directional antenna systems where they might purposely incorporate a tower (at a specific point in the array) tuned in such a way to create the desired pattern.
Very interesting Lewis - Thank you. I remember the introduction of ILR well. It was so welcome after just having those dreary BBC local stations and also brought FM stereo. Our local station was Radio Tees 257 and 95.0 VHF from Bilsdale. It was a great sound track for so many.
When I read "fire at a broadcast site" I was instantly reminded to the Calau/Germany broadcast tower fire in 2011. I was living in the area and half the state had no FM radio or TV (DVB-T) - about 1 million people. This area is flat as Holland and covered by high tower, high power transmitters (Grundnetzsender) covering large areas. That tower is some 180m high with the fire being in the upper part - firefighters could just watch it. I was happy to still have DLF on long wave for news and FM radio allowed some real nice DX with the clear spectrum. Rumor has it the fire was caused by Media Broadcast botching the adaption of the West German FM transmitters (several 100kW combined) to the East German cabling and antenna. Would make a fun story on Ringway's channel if happened in the UK.
Thank you for the history lesson, I find it odd that the temporary transmitter site was at the power plant for the London Underground at Lots Road and not the Battersea Power Station which has taller smoke stacks.
It is a crime the way that all the ILR stations have now been homogenised. It started with the big Heart rebrand and continued with Bauer. Love the IBA music at the end.
@@eadweard. Independent Broadcasting Authority. Former regulator of all independent broadcasting in the UK. Succeeded by ITC and latterly OFCOM through a number of mergers and reorganisations.They used to broadcast technical information programmes for the TV/radio trade until the end of the 1980s and the music is probably from one of these shows or the holding slide which would precede them.
It's dreadful. Someone made a wikipedia article for Greatest Hits Radio Yorkshire which is up for deletion as it isn't really a thing. The article lists all the independent local radio stations that were bought out and merged to make it :(
I know the history of the Saffron Green transmitter site very well. Saffron Green is near my Birth place of Barnet . I recall the temporary 539 and 417 khz days too . I live about 7 miles from this transmitter and the signal from 1548 and 1152 was very strong here. My Late Grandmother lived in Barnet and the signal was so strong there LBC and Capital could be heard all over the Medium wave dial.
I fully agree with your comments about the amalgamation of former ILR stations into homogeneous, corporate blandness. When ILR began just over 50 years ago it sounded fresh, innovative and different. All we have now is branding. A shame and a wasted opportunity for a truly independent local radio. This Saffron Green doc was fascinating from the get go! There is (was?) a similar array at Langley Mill near Minworth in the West Midlands which transmitted BRMB on 261 mw from February 1974. I think this transmission has since closed, a result of the apparent rush to close AM broadcasting. I enjoy your videos, even though they can be a little too technical for me sometimes!! Keep up the good work!
No, the sites not closed yet. Like Saffron Green the directional array at Langley Mill was used for two frequencies & is still in use by the BBC to transmit Asian Network programmes to Birmingham on the old Radio WM am frequency (1458Khz). ILR ceased from the site in 2020.
Interesting. I remember back in the 1990's holidaying in Menorca and the only UK station I could pick up in the evening was Capital Gold, it was absolutely rock solid every evening the whole time we were there for the two weeks.
ive been to this site, just next to the A1 southbound, between bignals corner,(south mimms) and sterling corner Barnet/Borehamwood, on the drone footage you can clearly see the cars on the A1 and the big grey buildings in the back ground are the new sky studios in Borehamwood, all my years living localy never new it was called saffron green, think its only kinda accessible via a dead end road off Barnet road, then a walk down a bridle way, do not try access via A1 too fast a road and no real areas to park.
Detuning an electricity transmission line tower is like when an amateur is detuning an element in their antenna farm that is having unwanted interactions with other antennas on certain bands. In the video you can think of it as a shunt fed vertical. I moved a clamped parallel pipe up and down the side of an old flagpole to change its tuning at my location like a jpole.
Loved the intro. 1975! Took me back to high school, wow. Driving my truck and listening to radio on an AC Delco AM-only radio with one speaker working. Ah, the lovely sound! Ha!
10:47 - Aside from the toroidal transformer and lightning bolt arrestor balls, my eye is drawn to the two feeder cables between the out-building and the mast. That single loop in the cable - is it intended as a low-budget inductor for transmitter/antenna impedance matching? I have observed it in numerous AM masts.
Good catch sir, seeing that obscure but important component! It's a lightning protection device. The single loop in the cable makes an inductor that presents a high impedance to lightning currents, "encouraging" lightning currents on the tower to jump the spark gap at the base and dissipate in the ground system...rather than try to find a path to ground through the antenna tuning network in the tuning shack and causing costly damage. This works because lightning has an extremely fast rise time whose currents behave like a VHF radio wave. The inductance acts like an RF choke for VHF. At medium wave frequencies and below, the inductance is insignificant and is compensated in the antenna tuning network. This is a simple old school protection system that works pretty well. Like many AM radio systems, it was probably invented and in wide use by the 1930's.
I'm always pleased to see someone else talking about the Austin Ring Transformer. They're just unmistakably cool, but must be kept clean and properly spaced, or (insert Johnny Cash's "Ring of Fire" here) 😆
Good old saffron green I have been well over 10 times I used to live 45 mins walk from the site in April 1974 capital and Lbc did not start from here until on test 01 March 1975 when capital went live in late may 1975 when we came back from Devon it had moved to 1546 and I still listen on 557 it says please tune to 1548 we are no longer on 557 than in 1985 the fire I went to have a look and there was a small portable cabin which was for LBC than other times I went there with my radio I miss capital gold 1548.
That is the 1920s developed BBC site. It has three sets of separate antennas that at one time carried four am services. Two directional antennas toward London & the third is omni-directional. It still carries BBC Radio 5 live, TalkSport & the Asian service Lyca Radio.
Mentioning the power having to be used from the site & the temporary transmitters used at Lots Road throws up another crazy fact. Both temporary frequencies covered the whole of London adequately with just a 1kW output due to the low frequencies used. The permanent frequencies, particularly 1548 required nearly 100 times that power following the site move & adjustments. Why go to all this expense when the lower frequencies were already cleared? Quite simply, the IBA had a hell of a lot of trouble getting the government to wrestle frequencies away from the BBC at the time, so having been allocated 1548 & 1152 KHz, they were determined to use them come what may.
Hi Lewis thanks for putting this video together can you tell me what power the transmitters put out I think you said LBC was 27 kilowatts was capital the same?I'm not interested in the ERP figures but the actually transmitter output thanksbin advance
LBC's transmitter output power was 5.5 kW on 1152 kHz. Captal Radio had a transmitter output power of 27.5 kW on 1548 kHz. The effective radiated power towards the centre of London was much higher due to the very directional nature of the aerial system - focused like a car headlight, with maybe just a few tens of watts radiated northwards.
Now that LBC NEWS has also stopped broadcasting, the beautiful transmitter will most likely be torn down sooner or later, believe me ;(( I'm already saying goodbye, it all started here with the connection to the medium wave. I always listened to gold radio 1548. I always listened to it at night ;((
I sort of remember the "coming soon" replays of tapes over the initial LBC and Capital frequencies in the early 1970s. Likewise they told you the new frequency to go to when they changed frequencies
Remember Capital radio coming on air. An amazing event given we only had Radio 1. Lived and worked in the London area as stations such as Magic and LGR launched. When Capital first stated on 95.8 it could be heard all the way out to Salisbury Plain! An exciting time.
With London having the choice of LBC and Capital Radio I was always swapping between them for a mix of Chart shows and some phone ins (Jeremy Beadle being one of the hosts plus the 1930s Jazz with Brian Rust) . Always difficult with not being shaw if I should listen to Charlie Gillett on BBC Radio London (I just didnt quite get into the genre - more appreciated than enjoyed), but Bob and Doug on morning LBC kept me informed of travel delays better
The comment about the tower lighting transformer isn't correct. It's called an Austin ring, and exists to couple the 220V (or whatever it is) on a 1:1 basis to the lighting circuit, while isolating it from the RF. The towers are RF live - without that the RF would couple to the power cable. There is unlikely to be any voltage transformation. Oh - and detuning - you basically make the structure into a folded unipolar antenna by dropping one or more 'skirt' wires from the top to the base, connecting them to the ground itself via a tuned circuit, which you adjust so the resulting 'antenna' is NOT resonant at the frequency of the nearby transmitter. You tune it to a different frequency!
Lewis, I need the name of that song on the outro. I've been looking for it for years now. TIA It's also hilarious that people are complaining that the music is only playing on the left channel
Regarding the VHF yagi, if it was indeed the aerial used for off air (back up) reception of 95.8 (Capital) and 97.3 (LBC) in the early years, this would have been from the IBA's tower at Croydon, not Crystal Palace. Crystal Palace transmits BBC Radio London (was GLR) on VHF - The Croydon tower transmits Capital and LBC on VHF (initially 2KW mixed pol. in the 1970's, but from the 1990's at 4KW).
and of course since the late 80's the services of Capital and LBC on MW and FM have been different, so any off air from Croydon would be the wrong content
@@StuartClary Indeed. Once the split AM and FM services were introduced in the late 1980s, the AM transmitters would have had to have entirely separate feeds.
@@mikesmith5139 The yagi is a relatively new addition. Any off-air backup would have to be from local DAB, as the FM frequency used by LBC in London carries a different service (1152 carries LBC London News, 97.3 carries the main LBC service).
Got a question you don’t thing one day you can get a tour inside the builder that hold the equipment that transmits the frequency I’ve always been interested in that
Technology is changing which will sadly and inevitably result in the loss of such places in time, but they ought to be celebrated like this along with the services they once carried and indeed still carry today. They're part of our heritage and regardless of whether you're a radio or transmitter aficionado like most of us here they will have had an impact on your life at some point. Documenting this stuff now will preserve its history for the day when the site is yet another 'disused' logo on a map. 🙌
Interesting on two counts for me as I watched Saffron Green go up as a kid, we passed the site all the time on the A1 we only lived a few miles away , but also the transmitter at Lots Road (the former London Transport Power Station), I used to visit the station fairly regularly towards the end of it life, I was told then the transmitter there was filling in a gap for the BBC but you mite want to investigate that , I remember there was a piece of out of service equipment just outside the compound with the working equipment a single wire going up the the top of the easterly stack. If you were down at Saffron Green did you go across to Brookmans Park there is a public foot path goes through the site , I used to use it as a kid
The site was never used by the BBC, as there are three separate antennas at Brookmans Park, so reconfiguring on the existing site would have not been a problem. The East mast at Saffron Green does indeed have a sloping wire reserve antenna, which was in use by Gold until it closed recently (see other posts for more details).
@@G600-uv8cs I didn't say Saffron Green was BBC , I wa talking about the antenna at Lotts Road and I was only reporting what the power station manger told me.
@@BerlietGBC The IBA ceased to use Lotts Road in 1975. It was bought back into use in 1978 as an infill site for BBC Radio 4 using LBCs old frequency (720Khz)as the 198Khz Long Wave service used by Radio 4 could not penetrate some buildings. Later still the old Capital frequency (558Khz) was re-allocated to Spectrum Radio.
@@G600-uv8cs I wish I had taken some pics of it at Lots Road at the time , sadly I didn't have my camera with me being digital I could take it with me in the station as being close to the sets would wipe it .
I fully expected a matching cheesy voice to that intro like Dave Lister's Confidence! "Well Hello! If you like transmitter sites, then you'll LOVE Saffron Green!" But seriously though ..... only 0.000000121 JiggaWatts ?!?!?!
Hmm, interesting site. I just looked on MB21 for this site and apparently the reserve aerial is in use now given the damage to the main aerial array. I'm not surprised given how Medium Wave is being shut down by a significant number of radio stations and operators, in favor of DAB and internet streaming. Note - the last time I used Medium Wave was listening to Smooth East Anglia on 1152kHz, 1170kHz and 1251kHz on the way back from a holiday in East Anglia. This was just before the closure of Smooth's Medium Wave transmitters.
The reserve antenna was only being used to transmit Gold on 1548, as only one of the ATUs on the tower that was struck failed. I live 10 miles to the NW of the site, & Gold was almost unlistenable due to distortion after the lightning strike. When the reserve was eventually switched on the power increase on 1548 was significant with signal quality nearly as good as from the BBC site at Brookmans Park. The signal on 1152 never changed at all.
2:40 - the former London Weekend Television building on the right there is now currently being demolished. More cultural vandalism of our broadcasting heritage! 😞
Worse transmitter station fire I’ve seen was on the teardrop island off the SE coast of India. Over $20-million in losses. 2+years recovery. Marconi B6146 grid box modulation (1x4) in flames durring commissioning and certifying phase. Very regrettable ended Marconi. circa 1998.
With regard to the final question of what is still transmitted from Saffron Green. My understaning is that, after (Capital) Gold was switched off in 2023, LBC News continued, as it always has, on 1152 Khz directional, southwards, across London using all four masts at 23.5 kW effective radiated power. My guess (and it's only a guess) is that LBC / Global will continue with this medium wave / AM transmission because the BBC's speech station Radio 5 Live continues broadcasting on medium wave from Brookmans Park on 909kHz. However the BBC will likely close this in the next couple of years, as the AM transmitter closures continue. Once Brookmans Park is switched off, LBC will also close from Saffron Green. That's just my guess, of course. Global may choose to switch off 1152 kHz from Saffron Green before the BBC switch off Radio 5 from Brookmans Park! Place your bets!
@@mikesmith5139 A lot of the Smooth Radio closures were aligned with the end of local advertising contracts, which is why the south coast am frequencies in Kent & Hampshire continued for several months after the others closed. Smooth Cheshire 1260 (Wrexham) is still operating now, & along with LBC on 1152 are the last am services still operated by Global.
Not odd numbering per se, just coincidentally on some channels. Europe has channels spaced by 9 kHz. US (eg) has them spaced by 10 kHz. In fact, at the high-frequency end of the MW band, the spacing (at the time these commercial stations began) it was merely 8 kHz, the historic result of too many stations (from different countries, only partially coordinated) being squeezed-up at that end of the band (kind of like unplanned handwriting reaching the far edge of a line/page).
There were historically a few places in Britain where saffron growing was a business. I wonder if this was one of them. Nowadays almost all saffron is grown in Iran.
Those transformers are called Austin Ring transformers and the air gap to prevent RF arcing is the key part.
The mast lights isolation transformer provides an air gap between the primary and secondary. The primary of the transformer is at ground potential, the secondary is at RF potential.
That answers a question I’ve had for 20 years. Thanks !
Absolutely use for isolation these are required in at least some radio broadcasting installations where are tower lights not sure if this is 100% always but but I'm aware of how the system works and as to how some radio transmission antennas do you need to be isolated from ground AKA insulated from ground.
For example some radio towers themselves are also an antenna in some setups.
All kinds of weird stuff can happen with RF and broadcasting and more.
For example years and years ago at one of the churches I attended for folks and my father worked there.
Every time an emergency vehicle would pass you actually hear the emergency radio on the PA system apparently it had something to do with certain parts not being shielded properly or not properly connected regarding shielding.
It was said several times that it may have had something to do with actually eat the output wiring not the input which I kind of doubt it's dubious that had to do with the speaker end of things with the wiring since that almost makes no sense but I suppose that if something was not quite right or otherwise something weird going on could be a factor.
The weird thing is that was the only thing that would come through on the system no other type of Mobile Radio interference almost like that someone was just the right length or something was acting as an incidental tuner and happen to be Quorum Court accidentally receiving this frequency.
It was only one of the emergency services in the area no other types of radio or anything just confirming this.
There was one of the other things of interest I remember years ago living in a townhouse in Wisconsin for a while.
There was a pretty high power radio station just literally probably capital city blocks don't know how far it actually was it was hard to tell from looking out a window you know.
But I can tell you you would actually hear that radio station on all kinds of stuff that was not intended to even receive radio.
Even occasionally when you pick up the way my phone and it's quiet you would even hear the station playing in the background!
It wasn't always just equipment that was just cheaply made or older you would even get some stuff on unintended things even if a bit better built.
It's not what was being transmitted that was a problem it was what was receiving it accidentally what's the actual issue.
Not the first time I've seen something like this and heard about it either on a personal basis that was.
Also that Rusty bolt affect with interference is really something else give me a real head scratcher for someone as well I knew someone that had this problem and that was damaged radio operator literally just a bad bones of connection on the tower that was causing interference that one for sure if you don't know what you're looking for could really rack your brain
@@aaronbrandenburg2441 Thanks for your comment. Some great points there.
You too watch jeff gearling lol
In the 70s and 80s in a city in South Florida, two of the telephone switching Central Offices, had massive amounts of AM RF from an AM radio station @ 50,000 watts day pattern 8 miles away. We were a user of dedicated Radio Pairs from our Public Safety Radio Network in the CO. We had to use grounding, Chokes, ferrite beads, the works to suppress it..
Good times @@aaronbrandenburg2441
Directional AM arrays are very common in North America. They have been used since the 1930s to both increase the signal strength in the direction of desired coverage areas and to reduce it in the direction of other stations on the same frequency. And nearby power lines and cell phone towers do often cause problems with the directional pattern and require detuning.
One AM station here in NJ recently gave up using their directional nighttime signal and reverted to a less powerful non-directional signal due to constant problems with this, and because most of their listeners are now tuning in their FM translators instead of the AM signal.
Saffron Green is still being used for LBC. When you drive past it on The A1, which is north and west of the site, the signal drops significantly as you pass the array.
I'm less than two miles from that site and I've been an SDR hobbyist for about 8 years now. I went though a phase of chasing NDB signals and I presume it was those transmitters that would sometimes bleed over into the 350-550 kHz part of the spectrum. I concluded that they must turn the signal strength up and down according to the time of day and the atmospheric conditions. As an aside, I can still pick up a raspy signal from those powerlines, in the LF and VLF bands. They run less than mile from my house. Rain seems to play a part in that, possibly just in the fact that I have a better earth when the soil is wet. I've walked around that area several times. There does not seem to be an actual place called Saffron Green, nor is there a clear history about a place with that name. There are one or two scattered houses and caravans there and there is a primary school with that name, nearby in Borehamwood. It's an odd name when you think about it - yellow green! Just like the grass around the towers. Those warning lights are important, the masts are near the approach for Elstree Aerodrome.
I have an AM transmitter less than a mile away, and have observed something similar to what you have. I think I’ll start logging my findings from day to day
@@ShawnWrona I'm guessing it's also a result of the front end of the receiver. Like everything else, the more you pay the better it is! I'm using an Airspy Discovery, which really is very good for the price, but I think there are other higher priced receivers that would not get so easily overwhelmed. I think when you are close to a large transmitter, especially with a long-wire antenna, the ground wave can be very strong. In terms of the transmitter control, I imagine they have some kind of measurement around the periphery of the area they intend, or indeed are contracted, to cover. The site here looks overgrown and dilapidated, but I would think there is some kind of remote monitoring and control. Propagation conditions must vary and it seems logical they would adjust the signal strength accordingly.
I admire your research, well done!
virticle structures can be detuned. They get a skirt attached to the structute. The reactance is measured and an appropriate amount of inductance or capacitance is added to cancel th X on the structure. fine tuning can be acomplished with a field intensity meter.
The Toroid coils are known as austin ring transformers, as you mentioned they decouple the AC service from being directly connected to the tower, in order to feed the tower lighting. Also notice the 2 ball looking devices next to the transformer. Those are adjusted to create a spark gap that will dissipate lighting strikes to ground. The detuning process is typically running wires from top to bottom with a tuning unit somewhere (usually at the base), without a lot of techno babble, it's tuned to make the tower essentially invisible at the operating frequency (s) of the nearby transmitter. The goal is to reduce or eliminate reradiation that would effect the pattern of the directional array.
No no, this is absolutely the audience that likes techno babble. Hit me with it, man..... I kind of get what they're doing, my question is how do the tuning boxes achieve making the tower effectively non-reactive to the signal....or, I suppose transparent (which sounds like they let the tower resonate, but only slightly so that to the RF wave there is effectively no change in 'refractive index' (IDK if thats right for RF, but ya know....the thing photons do, but RF) across the towers location)?
Full disclosure, I know the secret of all RF technicians.....In order to get your final certification level you have to sacrifice a chicken over your tool bags. Only then can you begin practicing the deep dark RF voodoo.....
@@TankR It's mostly black magic but the end game is to make the subject tower non-resonant at some frequency, typically where there is a standard broadcast transmitter nearby. The AM transmitter can radiate a significant amount of power (depending on licensed power, antenna configuration, etc.) up to a couple of miles from the transmitter site. If there is another tower nearby, some of that power can be re-radiated, thus skewing or distorting the original AM signal. There's a decent amount of information out there, google "detuning skirts" you'll find all kinds of info about the theory and implementation behind them. Interestingly the theory behind detuning stray towers is also utilized with certain AM directional antenna systems where they might purposely incorporate a tower (at a specific point in the array) tuned in such a way to create the desired pattern.
I worked at Lots Road for many years and I never realised about the antenna that were there. Took me back in time though.
I'm just mad about Saffron
Saffron's mad about me
I'm-a just mad about Saffron
She's just mad about me
Very interesting Lewis - Thank you. I remember the introduction of ILR well. It was so welcome after just having those dreary BBC local stations and also brought FM stereo. Our local station was Radio Tees 257 and 95.0 VHF from Bilsdale. It was a great sound track for so many.
When I read "fire at a broadcast site" I was instantly reminded to the Calau/Germany broadcast tower fire in 2011. I was living in the area and half the state had no FM radio or TV (DVB-T) - about 1 million people. This area is flat as Holland and covered by high tower, high power transmitters (Grundnetzsender) covering large areas. That tower is some 180m high with the fire being in the upper part - firefighters could just watch it. I was happy to still have DLF on long wave for news and FM radio allowed some real nice DX with the clear spectrum. Rumor has it the fire was caused by Media Broadcast botching the adaption of the West German FM transmitters (several 100kW combined) to the East German cabling and antenna. Would make a fun story on Ringway's channel if happened in the UK.
Great bit of broadcasting history.
I wonder what it sounded like during the fire and lightning strike. Like it it just suddenly cut off or if it was like distorted or something.
“1.21 Gigawatts?!? Great Scott!!” -Doc Brown
"1 point 21 kilowatts?!?!?"
1548 and 1552? I am surprised 2 channels can have just a 4Khz separation without any interference. I thought 10 was the normal separation.
@@southcalder quite correct. I hope you got, and enjoyed the reference though 😉
@@GeorgeZ2131548 and 1152 kHz
121,000 Watts are 151 kilowatts or 0.151 gigawatts or if you like 151,000,000 milliwatts.☺
A nice touch making the radiation pattern maps look like old school 'Engineering Announcements' graphics 😃
Thank you for the history lesson, I find it odd that the temporary transmitter site was at the power plant for the London Underground at Lots Road and not the Battersea Power Station which has taller smoke stacks.
It is a crime the way that all the ILR stations have now been homogenised. It started with the big Heart rebrand and continued with Bauer. Love the IBA music at the end.
What's IBA?
@@eadweard. Independent Broadcasting Authority. Former regulator of all independent broadcasting in the UK. Succeeded by ITC and latterly OFCOM through a number of mergers and reorganisations.They used to broadcast technical information programmes for the TV/radio trade until the end of the 1980s and the music is probably from one of these shows or the holding slide which would precede them.
@@dw7920 Thank you for explaining! Very interesting.
It's dreadful. Someone made a wikipedia article for Greatest Hits Radio Yorkshire which is up for deletion as it isn't really a thing. The article lists all the independent local radio stations that were bought out and merged to make it :(
Nice bit of IBA music at the end. So 70’s
Engineering Announcements!
I know the history of the Saffron Green transmitter site very well. Saffron Green is near my Birth place of Barnet . I recall the temporary 539 and 417 khz days too . I live about 7 miles from this transmitter and the signal from 1548 and 1152 was very strong here. My Late Grandmother lived in Barnet and the signal was so strong there LBC and Capital could be heard all over the Medium wave dial.
Brookmans park is quite close. Not sure what AM stations are still broadcast from there
I think its still Radio 5, Talk and Sunrise on 1458 KHz. The hundreds of TV channels on the satellite uplinks.
I absolutely love the closing music :D
I fully agree with your comments about the amalgamation of former ILR stations into homogeneous, corporate blandness. When ILR began just over 50 years ago it sounded fresh, innovative and different. All we have now is branding. A shame and a wasted opportunity for a truly independent local radio.
This Saffron Green doc was fascinating from the get go! There is (was?) a similar array at Langley Mill near Minworth in the West Midlands which transmitted BRMB on 261 mw from February 1974. I think this transmission has since closed, a result of the apparent rush to close AM broadcasting.
I enjoy your videos, even though they can be a little too technical for me sometimes!! Keep up the good work!
No, the sites not closed yet. Like Saffron Green the directional array at Langley Mill was used for two frequencies & is still in use by the BBC to transmit Asian Network programmes to Birmingham on the old Radio WM am frequency (1458Khz). ILR ceased from the site in 2020.
@@G600-uv8cs Thank you!
End IBA music is so nostalgic for me. I used to force my mum to watch the announcement programmes.
If you want to hear a full clean copy, search for "Current Affairs" by Francis Monkman, which was the music used by the IBA Engineering announcements.
@1:05 PEEKABOO!!
Glad I wasn't the only one who saw that!
@@taneliwhatsoever4023 Where's ' Lewis '
Didn’t notice until I rewatched the episode, hey… what was that!? lol
Oh man!
Pee kaboom?
Interesting. I remember back in the 1990's holidaying in Menorca and the only UK station I could pick up in the evening was Capital Gold, it was absolutely rock solid every evening the whole time we were there for the two weeks.
ive been to this site, just next to the A1 southbound, between bignals corner,(south mimms) and sterling corner Barnet/Borehamwood, on the drone footage you can clearly see the cars on the A1 and the big grey buildings in the back ground are the new sky studios in Borehamwood, all my years living localy never new it was called saffron green, think its only kinda accessible via a dead end road off Barnet road, then a walk down a bridle way, do not try access via A1 too fast a road and no real areas to park.
Radio Clothes Line ! Made me lol . Radio Caroline . Nobody I know would understand why it's funny .
Great Stuff Lad
Bless Up
Any chance of doing a video of the radio array at Exmouth Western Australia?
Detuning an electricity transmission line tower is like when an amateur is detuning an element in their antenna farm that is having unwanted interactions with other antennas on certain bands. In the video you can think of it as a shunt fed vertical. I moved a clamped parallel pipe up and down the side of an old flagpole to change its tuning at my location like a jpole.
Saffron Green is people!
Loved the intro. 1975! Took me back to high school, wow. Driving my truck and listening to radio on an AC Delco AM-only radio with one speaker working. Ah, the lovely sound! Ha!
PEEKABOO....i see you [at 12 seconds] hahaha
Haha Andy Kirby
10:47 - Aside from the toroidal transformer and lightning bolt arrestor balls, my eye is drawn to the two feeder cables between the out-building and the mast. That single loop in the cable - is it intended as a low-budget inductor for transmitter/antenna impedance matching? I have observed it in numerous AM masts.
Good catch sir, seeing that obscure but important component! It's a lightning protection device.
The single loop in the cable makes an inductor that presents a high impedance to lightning currents, "encouraging" lightning
currents on the tower to jump the spark gap at the base and dissipate in the ground system...rather than try to find a path to ground through the antenna tuning network in the tuning shack and causing costly damage.
This works because lightning has an extremely fast rise time whose currents behave like a VHF radio wave. The inductance acts like an RF choke for VHF. At medium wave frequencies and below, the inductance is insignificant and is compensated in the antenna tuning network.
This is a simple old school protection system that works pretty well. Like many AM radio systems, it was probably invented and in wide use by the 1930's.
Love the 70's porno music intro. Not that I have seen any of that.... 😂
Nicked the music from the IBA Engineering Announcements for the outro.
Nice.
That power plant looks like the Battersea Power Station on the cover of Pink Floyds album Animals.
I'm always pleased to see someone else talking about the Austin Ring Transformer. They're just unmistakably cool, but must be kept clean and properly spaced, or (insert Johnny Cash's "Ring of Fire" here) 😆
look at the creepy man at 0:12 looking and hiding behind the building bottom right corner. WTF
Probably just him controlling the drone
@0:10 Who's hiding behind the transmitter building? Drone operator?
No Andy Kirby
Good old saffron green I have been well over 10 times I used to live 45 mins walk from the site in April 1974 capital and Lbc did not start from here until on test 01 March 1975 when capital went live in late may 1975 when we came back from Devon it had moved to 1546 and I still listen on 557 it says please tune to 1548 we are no longer on 557 than in 1985 the fire I went to have a look and there was a small portable cabin which was for LBC than other times I went there with my radio I miss capital gold 1548.
Just looking around on google earth, and i spotted a rarther intresting place called brookmans park transmitter between Great North rd and Kentish LN.
That is the 1920s developed BBC site. It has three sets of separate antennas that at one time carried four am services. Two directional antennas toward London & the third is omni-directional. It still carries BBC Radio 5 live, TalkSport & the Asian service Lyca Radio.
Mentioning the power having to be used from the site & the temporary transmitters used at Lots Road throws up another crazy fact. Both temporary frequencies covered the whole of London adequately with just a 1kW output due to the low frequencies used. The permanent frequencies, particularly 1548 required nearly 100 times that power following the site move & adjustments. Why go to all this expense when the lower frequencies were already cleared? Quite simply, the IBA had a hell of a lot of trouble getting the government to wrestle frequencies away from the BBC at the time, so having been allocated 1548 & 1152 KHz, they were determined to use them come what may.
Interesting!! Cheers!
Good story Lewis, Thanks
1.21 gigawatts! great scott
Hi Lewis thanks for putting this video together can you tell me what power the transmitters put out I think you said LBC was 27 kilowatts was capital the same?I'm not interested in the ERP figures but the actually transmitter output thanksbin advance
97.5
LBC's transmitter output power was 5.5 kW on 1152 kHz. Captal Radio had a transmitter output power of 27.5 kW on 1548 kHz. The effective radiated power towards the centre of London was much higher due to the very directional nature of the aerial system - focused like a car headlight, with maybe just a few tens of watts radiated northwards.
@1:05 🤣🤣
I just caught that out of the corner of my eye.
Now that LBC NEWS has also stopped broadcasting, the beautiful transmitter will most likely be torn down sooner or later, believe me ;(( I'm already saying goodbye, it all started here with the connection to the medium wave. I always listened to gold radio 1548. I always listened to it at night ;((
I sort of remember the "coming soon" replays of tapes over the initial LBC and Capital frequencies in the early 1970s. Likewise they told you the new frequency to go to when they changed frequencies
Remember Capital radio coming on air. An amazing event given we only had Radio 1. Lived and worked in the London area as stations such as Magic and LGR launched. When Capital first stated on 95.8 it could be heard all the way out to Salisbury Plain! An exciting time.
With London having the choice of LBC and Capital Radio I was always swapping between them for a mix of Chart shows and some phone ins (Jeremy Beadle being one of the hosts plus the 1930s Jazz with Brian Rust) . Always difficult with not being shaw if I should listen to Charlie Gillett on BBC Radio London (I just didnt quite get into the genre - more appreciated than enjoyed), but Bob and Doug on morning LBC kept me informed of travel delays better
The comment about the tower lighting transformer isn't correct. It's called an Austin ring, and exists to couple the 220V (or whatever it is) on a 1:1 basis to the lighting circuit, while isolating it from the RF. The towers are RF live - without that the RF would couple to the power cable. There is unlikely to be any voltage transformation.
Oh - and detuning - you basically make the structure into a folded unipolar antenna by dropping one or more 'skirt' wires from the top to the base, connecting them to the ground itself via a tuned circuit, which you adjust so the resulting 'antenna' is NOT resonant at the frequency of the nearby transmitter. You tune it to a different frequency!
I just found this useful article: ncjweb.com/features/novdec05feat.pdf
Lewis, I need the name of that song on the outro. I've been looking for it for years now. TIA
It's also hilarious that people are complaining that the music is only playing on the left channel
Nevermind, I just found it. "Current Affairs" by Francis Monkman
Regarding the VHF yagi, if it was indeed the aerial used for off air (back up) reception of 95.8 (Capital) and 97.3 (LBC) in the early years, this would have been from the IBA's tower at Croydon, not Crystal Palace. Crystal Palace transmits BBC Radio London (was GLR) on VHF - The Croydon tower transmits Capital and LBC on VHF (initially 2KW mixed pol. in the 1970's, but from the 1990's at 4KW).
and of course since the late 80's the services of Capital and LBC on MW and FM have been different, so any off air from Croydon would be the wrong content
@@StuartClary Indeed. Once the split AM and FM services were introduced in the late 1980s, the AM transmitters would have had to have entirely separate feeds.
@@mikesmith5139 The yagi is a relatively new addition. Any off-air backup would have to be from local DAB, as the FM frequency used by LBC in London carries a different service (1152 carries LBC London News, 97.3 carries the main LBC service).
1.21 (x10^-4) GW. In case of a lightning strike, 1.21GW.
Got a question you don’t thing one day you can get a tour inside the builder that hold the equipment that transmits the frequency I’ve always been interested in that
I have calculated the amount of coax I would need to connect my home qth to Saffron Green's antennas. Sadly it is unaffordable. 73
I dig the 1970s sitcom intro! Also the changeup in outro music.
Can you do anything on pirate radio stations and do some of these in Liverpool and the Wirral and Leicester thanks
Technology is changing which will sadly and inevitably result in the loss of such places in time, but they ought to be celebrated like this along with the services they once carried and indeed still carry today. They're part of our heritage and regardless of whether you're a radio or transmitter aficionado like most of us here they will have had an impact on your life at some point. Documenting this stuff now will preserve its history for the day when the site is yet another 'disused' logo on a map. 🙌
Technology is changing, but to keep saying digital is better etc is not always true, sometimes analogue, is, in fact better.
Love the retro vibe. Great looking old site. Maybe an RF spectrum analyser could be taken there to see what's transmitting?
Interesting on two counts for me as I watched Saffron Green go up as a kid, we passed the site all the time on the A1 we only lived a few miles away , but also the transmitter at Lots Road (the former London Transport Power Station), I used to visit the station fairly regularly towards the end of it life, I was told then the transmitter there was filling in a gap for the BBC but you mite want to investigate that , I remember there was a piece of out of service equipment just outside the compound with the working equipment a single wire going up the the top of the easterly stack.
If you were down at Saffron Green did you go across to Brookmans Park there is a public foot path goes through the site , I used to use it as a kid
The site was never used by the BBC, as there are three separate antennas at Brookmans Park, so reconfiguring on the existing site would have not been a problem. The East mast at Saffron Green does indeed have a sloping wire reserve antenna, which was in use by Gold until it closed recently (see other posts for more details).
@@G600-uv8cs I didn't say Saffron Green was BBC , I wa talking about the antenna at Lotts Road and I was only reporting what the power station manger told me.
@@BerlietGBC The IBA ceased to use Lotts Road in 1975. It was bought back into use in 1978 as an infill site for BBC Radio 4 using LBCs old frequency (720Khz)as the 198Khz Long Wave service used by Radio 4 could not penetrate some buildings. Later still the old Capital frequency (558Khz) was re-allocated to Spectrum Radio.
@@G600-uv8cs I wish I had taken some pics of it at Lots Road at the time , sadly I didn't have my camera with me being digital I could take it with me in the station as being close to the sets would wipe it .
Groovy baby nice one
Who's that peeking around the corner of the transmitter building in the intro?
I fully expected a matching cheesy voice to that intro like Dave Lister's Confidence! "Well Hello! If you like transmitter sites, then you'll LOVE Saffron Green!"
But seriously though ..... only 0.000000121 JiggaWatts ?!?!?!
LBC left MW at the end of October 2024. I expect the future is not good for Saffron Green.
Hmm, interesting site. I just looked on MB21 for this site and apparently the reserve aerial is in use now given the damage to the main aerial array. I'm not surprised given how Medium Wave is being shut down by a significant number of radio stations and operators, in favor of DAB and internet streaming.
Note - the last time I used Medium Wave was listening to Smooth East Anglia on 1152kHz, 1170kHz and 1251kHz on the way back from a holiday in East Anglia. This was just before the closure of Smooth's Medium Wave transmitters.
The reserve antenna was only being used to transmit Gold on 1548, as only one of the ATUs on the tower that was struck failed. I live 10 miles to the NW of the site, & Gold was almost unlistenable due to distortion after the lightning strike. When the reserve was eventually switched on the power increase on 1548 was significant with signal quality nearly as good as from the BBC site at Brookmans Park. The signal on 1152 never changed at all.
Nice 1.8 160 meter antenna i would hook my radio up and work the world very interesting
Its interesting to note the contact number on the side of the building is a Wakefield number 01924, I presume Emley Moor is the point of contact.
Capital These days is Pretty much FM & Dab And pretty much everywhere
Lewis. 11:11 the 360-degree loop, lightening strike abatement?
Hey, I like your groovy lettering - - great vid, as usual.
2:40 - the former London Weekend Television building on the right there is now currently being demolished. More cultural vandalism of our broadcasting heritage! 😞
Worse transmitter station fire I’ve seen was on the teardrop island off the SE coast of India. Over $20-million in losses. 2+years recovery. Marconi B6146 grid box modulation (1x4) in flames durring commissioning and certifying phase. Very regrettable ended Marconi. circa 1998.
Is that Suggs peeping round the transmitter building at 1:05??
😂😂
He's hiding from his girl who was mad at him.
It’s Andy Kirby haha
Lord that music at the start is great, anyone know the name of it? 😊
With regard to the final question of what is still transmitted from Saffron Green. My understaning is that, after (Capital) Gold was switched off in 2023, LBC News continued, as it always has, on 1152 Khz directional, southwards, across London using all four masts at 23.5 kW effective radiated power. My guess (and it's only a guess) is that LBC / Global will continue with this medium wave / AM transmission because the BBC's speech station Radio 5 Live continues broadcasting on medium wave from Brookmans Park on 909kHz. However the BBC will likely close this in the next couple of years, as the AM transmitter closures continue. Once Brookmans Park is switched off, LBC will also close from Saffron Green. That's just my guess, of course. Global may choose to switch off 1152 kHz from Saffron Green before the BBC switch off Radio 5 from Brookmans Park! Place your bets!
@@mikesmith5139 A lot of the Smooth Radio closures were aligned with the end of local advertising contracts, which is why the south coast am frequencies in Kent & Hampshire continued for several months after the others closed. Smooth Cheshire 1260 (Wrexham) is still operating now, & along with LBC on 1152 are the last am services still operated by Global.
Why is the music only in the left channel?
1975 - that explains the dodgy stereo separation
Another rad video
Lewis, why are British station on odd numbers and we colonists are are an even number system?
Not odd numbering per se, just coincidentally on some channels. Europe has channels spaced by 9 kHz. US (eg) has them spaced by 10 kHz. In fact, at the high-frequency end of the MW band, the spacing (at the time these commercial stations began) it was merely 8 kHz, the historic result of too many stations (from different countries, only partially coordinated) being squeezed-up at that end of the band (kind of like unplanned handwriting reaching the far edge of a line/page).
1:16 Drone filming drone?
FYI: Your intro music is only playing on the left channel.
When I heard the thing June I thought 1970s theme tune obviously
Just hit the east side of the LBC
On a mission tryna find Mr. Warren G
I love your videos mate.
woot! i was born in '75 🕺
75? Was that the Captain Beaky era….. or was that later..ish?
Love it!! is that you hiding having a wee wee on the wall? heh heh......
Guh-rooo-veyyy ;) keep it up
Very interesting
My head Immediately filled with Jeremy Clarkson’s voice for some reason lol
Hi there! What's the song from 0:00 to 0:32?
Was thinking its a blue movie at first.
Confessions of a transmitter spotter
LOL i saw you
There were historically a few places in Britain where saffron growing was a business. I wonder if this was one of them.
Nowadays almost all saffron is grown in Iran.
sunny and Manchester very rare sight
It was 15 miles north of London!
@@RingwayManchester There you go!😂😂😂
hello from my tesla Y hf uhf vhf ham shack